Many large scale air conditioning systems rely on evaporative cooling towers as an integral means for removing heat from the air located within a building. Generally, air conditioning systems operate by passing air or liquid over coils through which a cold refrigerant, such as freon, flows. The refrigerant is cooled by first compressing the refrigerant in a gaseous state. Compressing the refrigerant causes the temperature of the refrigerant to rise. The refrigerant is then cooled by sending the compressed gas through a condenser. The compressed refrigerant condenses from a gaseous state into a liquid state as the temperature of the gas is reduced. The pressurized liquid is then sent through an expansion valve, which causes the refrigerant to evaporate and cool rapidly. Depending on the configuration of the system, either a gas, such as air, or a fluid, such as water, is cooled by contacting the coils through which the cold refrigerant flows. The cooled air or fluid is then circulated through a building to cool the air contained in the building.
The stage in which the refrigerant is cooled and condensed is typically conducted in a condenser. Often, but not always, the condenser is a heat exchanger having a plurality of tubes through which the refrigerant flows. The tubes are contained in a chamber through which a fluid, such as water or other coolants, flow. The fluid passes through the chamber and contacts the outside surface of the tubes through which the refrigerant flows. The fluid picks up heat from the tubes and is then circulated through a cooling tower to cool the fluid. Typically, the fluid must be pumped from the basement or boiler room of a building to the roof of a building, which may be more than 100 stories from the basement in the largest of buildings in the United States. The fluid is passed through an evaporative cooling tower, located on the roof, which cools the fluid. The cooling tower operates by forcing air across the fluid, which is typically water, as the water is dispersed through the cooling tower. A portion of the fluid evaporates, thereby cooling the fluid by taking heat from the fluid and releasing it into the air. The cooled fluid is then returned to the condenser through a conduit.
While a cooling tower increases the efficiency of a cooling system and has been in use for years, a cooling tower requires considerable maintenance to keep the unit in an operable condition. For instance, algae, slime forming bacteria, fungi and other microorganisms often form on baffles of a cooling tower that are used to disperse the hot water as the water flows past fans blowing air. The algae reduces the efficiency of the cooling tower and can clog the flow of water through various parts of a water tower. Currently, this problem is overcome by regularly removing the algae from the baffles and other parts of the water tower and by adding chemicals to the water on a regular basis to combat the algae and other growth.
Another problem that occurs in a cooling tower is the development of scale deposits. Scale deposits occur when solids and gases in a cooling tower reach their capacity of solubility and precipitate out onto piping and heat transfer surfaces. As the scale deposits on heat transfer surfaces, the ability of the cooling tower water to absorb heat is reduced. Scale deposits have been treated using chemicals. However, while chemicals allow a particular volume of water to hold a greater amount of particles, a point is reached where the water must be removed from the system and replaced, which is often referred to as bleeding the system. Because this water often contains chemicals, it must be disposed of in accordance with applicable environmental regulations, which can be very expensive.
A cooling tower relies on the evaporative cooling process to cool water by pulling heat from the water. The evaporative process causes considerable water loss from the water flowing through the cooling tower. Thus, in order to maintain the system in an operating condition, water must continuously be added to the system. In dry geographic areas and areas in which water is in short supply, water may be not be readily available in the amount needed. In fact, it is not improbable that some areas may even prohibit the use of water towers in the near future because of ever increasing political pressures to conserve water resources.
Thus, a need exists for a system for cooling a condenser fluid in an air conditioning system that does not rely on an external water source.